Outside of the City of Pittsburgh you have wide support, the reason being is the huge number of old Coal railroads that can be used and connected. Examples of these are the following:
Montour/Great Allegheny Passage/Panhandle trail (372 Miles without side trails, some parts are NOT finished yet, but most of the trial is up and bikable)):
Montour Trail (49 miles Between McKeesport PA and Neville Island Pa, with Cecil Pa at about the 25 miles mark.
http://www.montourtrail.org/Panhandle Trail (Between Cecil Pa and Weirton WV, 29 miles):
http://www.montourtrail.org/panhandle.htmlGreat Allegheny Passage (318 Miles between McKeesport PA and Washington DC):
http://www.atatrail.org/Other Trails (Still a work in progress more than a Completed trail):
West Penn Trail (East and North of Pittsburgh):
http://home1.gte.net/lennoxx0458/westpenn.htmlhttp://www.conemaughvalleyconservancy.org/Allegheny River Trail:
http://eagle.clarion.edu/~grads/avta/ART.htmlGhost Town and Hoodlebug Trails (Indiana and Cambria County also referred to as the Tri-County Trail for it will connect the County seats of Indiana, Cambria and Blair County).
http://www.indianacountyparks.org/parks/gtt/gtt.htmlhttp://www.indianacountyparks.org/parks/ht/ht.htmlThe above is the good news, the Bad news is the City of Pittsburgh while adopting a "bike plan" have NOT done anything to implement it nor do anything to make Pittsburgh more bike Friendly. Thus Pittsburgh holds its place as the Second worse (Second to New York city) for biking:
Various Pittsburgh Plans for Bikes:
http://www.portauthority.org/pdf/RRR.pdf#search='Pittsburgh%20bike%20Trail%20plan'http://pittsburgh.about.com/gi/dynamic/offsite.htm?site=http%3A%2F%2Fwww.city.pittsburgh.pa.us%2Fcp%2Fhtml%2Fbicycling_plan.htmlhttp://www.bike-pgh.org/index.htmlAnd finally if you believe bike trails are to narrow, what to try a four lane bike trail? It is only 8.5 miles long and has two two lane tunnels. It is the old Pa Turnpike, built in 1940 bypassed in the 1960s and now (or soon will be) a four lane bike trail:
http://www.pike2bike.com/history.htmFor more Pennsylvania Bike Trials:
http://www.dcnr.state.pa.us/railtrails/default.aspx